Fly repellent



United States flatent F FLY REPELLENT Willis N. Bruce, Champaign, Ill., assignor to Lee Ratner, Chicago, Ill.

The present invention relates to'new and improved fly repellents and fly repellent compositions and, while not strictly limited thereto, the invention is particularly concerned with safe and effective fly repellents and fly repellent compositions useful to farmers in the protection of their dairy cattle from biting as well as non-biting flies, such as house flies, horse flies, stable flies, horn flies, etc.

The hereinafter disclosed combination of repellent and fatty acid, pursuant to oflicial requirement is being made the subject-matter of my divisional United States Letters Patent application Serial No. 3,279, filed January 19, 1960.

There can be little doubt concerning the benefits derived from good fly control practices in terms of increased milk and meat production. Prior workers in this art have endeavored for some time'now to increase the fly control periods with a safe quantity of repellent in order to increase the benefits derived from good fly control. At present the commercially available cattle fly repellent sprays, when used at the recommended dosage of 2 ounces per animal, will give approximately 80 to 90% reduction in stable fly populations for a period of only 6 to 3 hours.

It is well known to entomologists that insects are quite specific in their response to repellents. As an example, mosquito repellents such as Rutgers 612 (2-ethyl-l,3- hexane diol), dimethyl phthalate, dimethyl carbate, Indolone (butyl ester of 3,4-dihydro 2,2-dimethyl-4 oxo- ZH-pyran-fi-carboxylic acid), etc., are of no practical value when applied to cattle in warding off the attack of biting flies. For this purpose other kinds of repellents were developed. Among these are Thanite' (isobornylthiocyanoacetate), Crag fly repellent (butoxy polypropylene glycol), Lethane 384, (beta-butoxy-beta-thiocyanodiethyl ether) and the activated pyrethrin sprays. None of these can safely be used in quantities to eflect a high order of fly control (90% repellency) for periods of more than a few hours. There also are serious implications of contamination of the milk when large quantities of these materials are used, as well as injury to the animal itself. Therefore, practical limits in dosage of active ingredients per animal must not be exceeded to produce beneficial results. Concentrate sprays can be applied safely to cattle if the quantity is limited to a few ml. per animal. All of these factors must be borne in mind when considering the present invention.

It is anobject of the invention to produce and provide fly repellents and fly repellent compositions which will give cattle a high level of protection from flies, not for just 2 or 3 hours, but throughout the day.

A further object of the invention is to provide fly repellents and fly repellent compositions which are safe, highly eflective for long periods of time and which greatly enhance methods of control widely used by farmers to protect their dairy cattle from biting and non-biting flies.

"It has now been found, inaccordance with the present invention, that the lower alkyl esters, suchas the n-propyl ice and n-butyl esters, of dicarboxylic acids, such as maleic, furmaric and succinic acids, afford safe, highly effective and long lasting fly repellency action for the purposes herein indicated, either when employed per se or in solutions or aqueousemulsions. Typical specific esters falling within the foregoing genus are di-n-propyl maleate, di-n-butyl maleate, di-n-propyl succinate, di-n-butyl succinate, di-n-propyl furnarate and di-n-butyl fumarate.

It is thought that safe repellents are those which if absorbed by the animal tissue would be readily metabolized into useable organic compounds. Since dicarboxylic acids seemed to be the most promising source of fly repellent esters, the desired intermediate metabolites (fumaric and succinic acids) were found in the Krebs cycle. For example, the butyl alcohol residue of the butyl esters when released within the body should readily oxidize to butyric acid and then decarboxylate to carbon dioxide and water. Thus constituted, di-n-butyl-succinate or di-n-butylfumarate, as well as the other esters, could safely be used in dilute or concentrated solutions upon animals, or as emulsifiable concentrates which are diluted with water or saturating spraying of animals. Acute toxicity tests with these esters indicate that they are innocuous.

It has been found, in accordance with the invention, that certain synergists when used in combination with the aforesaid alkyl esters of dicarboxylic acids, will render said esters much more eflective. This is a very surprising discovery because the synergists employed to increase the effectiveness of the esters are in and of themselves absolutely ineffective to repel flies. The synergists employed are piperonyl butoxide (3:4-methylene dioxy-6- propylbenzyl n-butyl diethyleneglycol ether), sulfoxide (n-octyl sulfoxide of isosafrole), M.G.K. 264 (N-Z-ethyl hexyl imide of endomethylene tetrahydrophthalic acid), Crag fly repellent (butoxy polypropylene glycol) and various unsaturated fatty acids and fatty acid esters. The discovery that these various fatty acids and fatty acid esters are synergists for the ester fly repellent of the present invention was even more surprising because these fatty materials not only do not repel flies but they are actually used in fly baits to attract flies.

v In order to test or evaluate the effectiveness of the fly repellent esters of the present invention,' as well as to test and evaluate the effectiveness of said repellents in combination with synergists, both laboratory and field repellency tests were carried out. First, with respect to laboratory tests, the following procedure was followed:

Weighed lactose pellets, used as bait, were placed upon filter paper which was impregnated with the test solution. The filter paper was folded, to form a slightly conical surface which prevented the pellet from being moved'by the flies. The actual procedure was as follows: The solution of the repellent in acetone was applied to the folded 5.5 cm. filter paper by means of a micropipette. In the case of the ester repellent, sufficient solution was used to leave 5 mg. of the repellent on the paper. When a combination of ester and synergist was tested, suflicient solution was employed to leave 5 mg.

each of repellent and synergist on the paper. The weighed pellet was placed'in the center of the paper after the solution had diffused evenly throughout the paper. Usually 20 to 30 minutes aging in a moist chamber (100% humidity) of F. were required for even distribution of the liquid. The filter paper with the pellet was then placed upon a turn table in an exposure cage. The turn table,

powered by a 4 r.p.m. timer motor, was in operation dur- I ing all exposure periods. The pellet could be removed from the filter paper at any desired period after treatment or pellets could be placed on the filter paper for hourly period after treatment. It was possible to obtain the over-all 24-hour repellency of a solution by allowing 2,93 ages 3 the pellet to remain in the cage for 24 hours before removal. Tests were conducted at a constant temperature of 80 F. and a relative humidity of 100%. As standard procedure, about 1 50 adult flies were .used for each filter paper to be tested. Usually ten to .twentypapcrs p l were po d s mu t nsqusl A pe let rem te; from test p p rs er d i di i nbven (60 6-), was hours and then reweighed. The amount of lactose lost y feeding ndisa e ati sps lens .13. 9 m te-- rials u since tb fly had o when the t s tsd filter paper during feeding. 7

Two sizes of lactose pellets were useda small 35 37 mg. pellet for short exposures, and alarger 78-80 mg. pellet for 8 to 24 hours or more ofeontinuous exposure. Constant illumination was provided by a 100-watt light bulb suspended approximately 12 inclies above the turn table cage. A 50ml. beaker containing a folded paper wick and water was placed in the center of the turn table to supply the flies with needed water.

The weight loss data obtained may be analyzed statistically or may be transformed into percent repellency by the following formula:

Original wt. of pellets mg.mg.

consumed by fiies- 100 Original wt. of pellet mg.

Percent repellenoy Laboratory repellency tests carried out in accordance with the foregoing procedure gave the following results for the indicated repellentor repellent composition:

Repellent dl-n-propylmaleate 100 F 00.0 00.0 00.0 dt-n-propylznaleate-l-piperonyl I butoxide... 100 F 23.2 00.0 00.0 dt-n-butylmaleate-.- 100 100 71.0 29.4 00.0 dl-n-butylmaleate+plperonyl butoxlde. 100 100 100 97.6 90.? dl-n-butylsucclnate 100 100 92,1 69.8" 27.4 dl-n-butylsuccinatefl-pliarohyl butoxlde-. 100 100 100' 98. 2 94.3 di-n-propylsuccinate 100 F 6.8 00.0 00.0 dl-n-propylsucclnate+piper0nyl butoxide" 10.0 100 89. 6 47. 8 15. 4 di-n-propylfumarate 100 100' 00.1 71.2 21.0 dl-n-propylfumarate butoxicle 10 0 100 100. 100 '95. 3 dl-n-butylfumarate 100 100 03.2 59.7 66.3 d mt t s atwmneronyl;

E-heptene-2,3-dicarboxinride3-- 100 100 100 95.2 -s9;o di-n-propylfungnrate-ksulfouide. 100 100 100 100 07.8 di-n-propylfumarate-l-M.G.K.264 100 100 100 98.3 91'. 2 d'l-n-butylfumarate-l-sulfoxide.-. 100 100 100 100 94. 8 di-n-butylfumarate-kM. G.K.264 100 100 100 96. 0 93. 7 dl-n-butylmaleate-l-sulfoxide 100 100 100 95. 8 90. 1 di-n-butylmsleate-l-M.GIL-264 100 100 100 90. 6 83. 5 di-11-propylmaleate+sulfoxide 100 F 25; ;2 00. 0 00. 0 piperonyl butoxide- F 0.0.0 00.0 0 0 .0 M.G.I .264 F 00.0 00. 0 0 0 0 Sull'0xide V F 00.0 00.0 0 0 0 Rutgers 612. F 00. O 0 0 0 Rutgers 612=piperonyl butoxide. F 00. 0 0 0 0 dimethyl c-arbate u F v 00.0 0 0 0 Thanite 95.6 83.7 64.0 23.0 00.0 di-n-butyl-succinate+Thanite.. 100 100 90. 2 82. 6 28. 7 di-n-butylsuccinate+oleic acid, 100 100 100 96. 1 87.0 di-n-butylsuceiuate-l-lard oll' (Armo extra winter strained)- -L- 100 100 97. 4 00. 2 '50. 8 dl-n-butylsuccinate+plopyl oleate. 100 100 00.2 91.4 77. 2 di-n-butylsuccinateq -benzyl oleate. 100 100 100 95. 5 0 5. 9 dl-n-butylsuceinate-i- Crag Fly Rei pellent... 100 100 100 96.0 88.9 di'-n-butylsuecinate+ste c 100 100 87 .2 61.0 d!sn:butylsucclnate+Petro1atum (US na).- 0 -2 5 -5 leie ac1d p 0.0 Lard Oi1 0.0 Saturated fatty acids and yd carbons 0.0

is attractlve'retheithan repellent, if 7 7 L b ra ory te t were a s carr ed su tfis -dete mine h ptim m r iqsf e te repel en t yns si tt a NO-mgspellsn an synsrsist wa 'a d .5 m-filtsrpaperend aged at 9 F-;es.. 06%

69% aft ss m nati $1 thelfisld t s a 7 'x lat nsquam of thre may humidity for 20 hours. The results of these tests are tabulated hereinbelow:

Repellent, Synerglst, Ave. Percent di-n-butylsull'oxlde, Repelleney sueelnate, mg. or three mg. group:

10 0 92. 8 a 2 96.1 "6 4 08. 3 5 s :0 4 6 93.3 2 s 44.5 0 10 6. 5

di-n-butylsulfoxide, Percent tumarate, mg. Repellency di-n-butylpiperonyl Percent succinate butoxlde, Repellency mg. mg.

dl-n butyloleic acid, I Percent "suce nsts. 1 8- 91 091 95- t i l be s n rom h f egoing table tha hen st sp l n -syns st combin ns ar mp oy d. e t resu t are-ob a n d whe the 'synq s st smp' i ss m blacks wa employ to es thee iab li y 0f a a sed in th fi d n to d mine the r t e me it of various cattle sprays in repelling horn and stable flies.

To init a e t is e per e t t w nece y t p termine the relative susceptibility of all the animals in hehs h s a a mp h d y ec rding t e berof flies on each animal at 10 a.m., 1 pin, and 3 pm.

for 11.36 days. The animals were then grouped accordsj. ing to their relative attractiveness to horn andstable flies. Three three-cow groups thus balanced for uniformi ty in fly attractivity were selected for testing.

Th anim s e ated wit appro ma e oz. of pr y per an ma appl ed b means o an s milins prayer, at 6 91. days hen the temp rature a srpss sd t sisses fir w ss se r-{ pe t tested a 2% solution in a cattle spray-base oil'yvas em plsm sl. and when t e estsr s nersists mbinatiqnwa empl ed. a

er tested fa a h mete -i;

'smnlo sd a mineral oil radios: ha in density '0; 51 S. 1

e spra ba e-oi awmi s-2% es @1295 7. ma ts-1 t w s emplo e In spmsin tanse t ese.

ee was 2% di-n-butylsuccinate 2% di-n-butylsuccinate with 5% sultoxide 2% di-n-butylfumarate 2% di-n-butylfumarate with 5% sulfoxide 2% di-n-propylt'umarate 2% di-n-propyliumarate with 5% suloxide 2% di-n-butylmaleate 2% di-n-butylmaleate with 5% sulioxide 3% Thanite 0.1% pyrethrins, 1.0% sulfoxide, 5% Crag fly repellent 5% di-n-butyliumarate 5% di-n-butylsuccinate 1.0% pyrethrins with sulfoxide--. 30% Crag fiy repellent 2% di-n-butyliumarate with 5% piperonyl butoxide 2% di-n-butylsuccinate with 5% piperonyl butoxide 5% sulioxide 5% piperonyl butoxide 2% di n-butylsuceinate with 2% malathion (0,0-dimethyl .dlthiophosphate of diethylmercaptosuceinate) 2% malathion alone once In order further to evaluate the addition of oleic acid, as well as other unsaturated fatty acids, to the repellents of the present invention, and also to ascertain the desirability of the addition of other additives, another series of laboratory tests was conducted in a manner heretofore set forth. In the tests, 10 mg. di-n-butyl succinate were used with each additive. Percent repellency of various mixtures of repellent and additive was determined by applying the mixture to 5.5 cm. filter papers and exposing the treated papers to flies. The following results were observed:

iter- 5 Additive 10 mg. Span 85 (sorbitan trioleate) 10 mg. Span 80 (sorhitan mono-oleate) 10 mg. Atlox 3335 (polyoxyethiene sorbitan esters of mixed fatty and resin acids) 10 mg. Triton X100 (alkyl arylpolyether alcohol) 10 mg. 8-1956 (emulsifier containing 77% modified phthalle glycerol alkyd resin in ethylene dichloride).. 10 mg. Rutgers 612 10 mg. Dimethylphthalate 30 mg. olive 30 mg. corn oil. 30 mg. H-C resin (hydrocarbon synthetic resin) 30 mg. palmitic acid 30 mg. iaurie acid. 30 mg. stearic acid..' 30 mg. par 30 mg. caprylic i 30 mg. linoleic acid 30 mg, riflinnlaip The foregoing results show that additions of various amounts of oleic acid increase the repellency of the din-butylsuccinate. Unsaturated .fatty acids increase the repellency remarkably, whereas saturated fatty acids increase repellency only slightly. The various surfaceactive materials (Atlox 1045 A, etc.) increase repellency while mosquito repellents (Rutgers 612 and di-rnethylphthalate) do not significantly increase repellency.

As previously indicated, the repellents of the present invention may be applied per se to animals but in most cases it it desirable to employ the repellents with a carrier or vehicle, i.e., either in oil solutions or in emulsifiable concentrates. Actually, the amount of repellent or repellent mixture in the carrier or vehicle may be varied over extremely wide limits but it is recommended that not less than 2% repellent be included in any repel lent-vehicle mixture. When oil solutions are employed, a'2% to 5% repellent-in-oil solution is used on animals at a rate of 2 oz. per head for 24-72 hours of protection. ,Synergists and additives may be used in concentrations of 2% to 10% to extend repellency beyond 72 hours. For 2 to 7 days protection, 5% to 20% repel- Percent lent-in-oil solutions are employed and 5% to 95% syn- Addmve gagi g; ergists and additions may also be employed. Emulsion treatment concentrates may be made up of 20% to 90% repellent with 10% emulsifier such as Atlox 1045-A, the re- Nona id 00.0 mainder comprising an additive or synergist, the amount.

i'ffiffii 25 3 of emulsifier being variable according to the stability of 10 mg. oleic aeig 97. 8 emulsion devised.

28:35: 3 5,333,; $813 In formulating repellent-in-oil solutions, mineral oil g a nn 100-0 fractions are desirable as carriers of diluents. The folf f, giifgj f fff fff j jiff f 5m lowing diluents have been satisfactorily employed:

Composition Code No. Oil Mol. Microdye Analysis NDM Method Percent Wt. U.R.

Percent Percent Percent Percent Percent Percent PN 0 a P N a L-zes'l No. Q 198:1:5 as Trace 4 73 27 0 96. 0

1.4542 Min. Seal 245=1=10 s7 0 13 62 a1 7 93.8

L-s715 N-Octadecane--- 254.4 100 0 0 100 0 0 100.0

1.4042 Eur 2ss=1=5 100 0 0 66 34 0 100. 0

L-53 Acme. 324:1:10 02 0 s 64 a4 2 91. 0

L-ili Premier 330:1:5 98 o 2 64 36 0 100.0

Ir83 SuperlaNo. 10.. 352 97 0 3 35 0 100.0

Viscosity, Ave. line Gravity Sp. Gr. 50% Dist. Rel. Sp. Dis- Code No SSV at Carbon Pt. C.) API) at 20 0. Pt. F.) Index persion 1s 72. 7 45. s 7850 r 420 1. 4410 103. 2

42. s 1s 83. 5 s7. 4 8345 570 1. 4632 10s. 0

79. 4 22 as. 2 as. 0 352s ass 1. 4102 105. 4

75. 7 22 102. 5 s5. 1 8460 681 1. 4040 0a. a

nose-sac Tests were carried out to determine the optimum ratio ofrrepellent to oil solvent. In the tests, oil solvent No. E6942, identifiedin the above table, was employed with 10 mg. of di-n-butylsuccinate. Various amounts of oil were used, with the repellent, on 5.5 cm. filter paper-and tested 72 hours after treatment. The followingresults were observed:

e o oil pe 5.: cm paper: Perce t ehe en y The foregoing results illustrate that oils such as L-6942 are advantageous when added to the repellents in any desirable ratio.

Tests were also carried out to determine the optimum performance of ,di-mbutylsuccinate (BS) and .di-butylfumarate (BF) with .oil diluents of various molecular isht In-eachsase, 0me of r pellent wa u e wi h 20mg. of oil on:eaeh-.5.5 cm. filter-paper. The followhis results werefobservedz Percent Repelleney of Average 5.6 cm.tllter 0,11 Qode No. 7 Gran: Repellent papers 48 hrs.

' f Molecular after treatment o! 011 1 with oils containing repellents Acetone.--

From the foregoing it will be seen that oils of various molecular weights increase the repellency of surfaces treated with the mixtures. Optimum repcllency was obtained with oils of intermediate molecular weights (254-349).. t

In addition to the specific formulation employed above in the :field tests, thefollowing are given by way of u th ex ples:

Oil solution for daily application Emulsifiable concentrate for dilution -=with water Atlox 1045A p l0 Di-n butylsuccinate 32 Oleic/acid 53 Methoxychlor 5 It will be readily understood, of course, that in any of-the foregoingformulations, the divn-butylsuccinatemay be substituted by di-n-propylmaleate, di-n'-.buty1maleate di-npropylsuccinate, di-n-propylfumarate or di-n-butylfumarate and the oleic acid may be replaced by piperonyl' butoxide, n-octyl sulfoxide of iso-safrale, N-Z-ethyl hexylimide of iendomethylene tetrahydrophthalic acid, butoxypolypropyleneglycol, lard oil propyl .oleate,tbenzyl oleate, and stearic acid.

While it has been indicated herein that the repellents and repellent mixtures of the present invention have utility in the treatment of cattleso that the cattle will yield more butter fat .during the fiy season than they would if they were not protected, it will'be readily understood, of course, that the repellent and repellent mixtures may be and are used in other environments. For instances, the repellents herein disclosed are effective-to repel flies from hogs and horses. Moreover, the repe llents may be combined with other repellents, such as Rutgers 612, etc., and applied to humans. Thus, the

epe ents f the in ent on p ssess ut l ty in ep l in flies not only from cattle, but from other as well, and also iron; humans.

It will also be understood that the present repellents may be mixedwith known insecticides, such as DDT, etc so that as the repellent loses its potency and repellent power, the insecticides will :serve to kill those 'fiies not repelled.

What is claimed is:

, A comPQ i O comp is ng -n-b tyl maleate-and hy ene d nsy-fi-p py enzyl nutyl tdiethyl ne-i glycol ether). 2. .A composition comprising .di-nfbutyl succinate and.

(3:4-methylene dioxy-6-propylbenzyl n-butyl diethyleneglycol ether).

3. A composition comprising di-n-propyl suoeinate and (3 :4-methylene .dioxy-6-propylbenzyl n.-butyl .diethyleneglycol ether).

4. A composition comprising di-n-propylfumarateandn-octyl sulfoxide of isosafrole.

5. A composition comprising di-n-butylfumarate apdj -2-e y hexyl im de of endomethylene tetrahydr phthalic acid.

6. A process for repelling flies from warm-blooded animals which comprises applying to said animal a repellent composition comprising di-n-butyl maleate and (3:4-methylene dioxy-6-propylbenzyl n-butyl diethyleneglycol ether).

7. A process for repelling flies from warm-blooded animals which comprises applying to said animal a repellent composition comprising di-n-butyl suocinate and (3:4-methylene d-ioxyqfi-propylbenzyl n-butyl d-iethyleneglycol ether).

8. A process for repelling flies from warm-blooded animals wh-ichcomprises applying to said animal a repellent .composition comprising di-n-propyl succinate and (.3 -n1ethylens .dioxy-orpropy y y diethyleneglycol ether).

9 ..Aprocess tor repelling flies from warm-blooded animals which comprises applying to said animal a repellent composition comprising di-n-propylfumarate and p-octyl -sulfoxide of isosafrole.

10-. Aprocess .for repe flies from Warm-blooded n-z-ethyl hexyl inside of endomethylene tetrahydrophthalic acid.

enemas 11. A composition for repelling insects comprising, as a fepellent, a symmetrical diester of a 4-carbon atom dicarboxylic acid esterified with alkyl radicals selected from the group consisting of n-propyl and n-butyl and, as a synergist, a hetero-dicycliccompound selected from the group consisting of 3:4-methylene dioxy-G-propylbenzyln-butyl diethyleneglycol ether, n-octyl sulfoxide of isosafr'ole, and n-Z-ethyl hexyl imide of endomethylene tetrahydrophthalic acid.

12. A composition for repelling insects comprising, as a repellent, a symmetrical diester of a 4-carbon atom dicarboxylic acid esterified with alkyl radicals selected from the group consisting of n-propyl and n-butyl and, as a synergist 3:4-methylene dioxy-6-propylbenzyl-nbutyl diethyleneglycol ether.

13. A process for repelling flies from warm-blooded animals which comprises applying to said animals a symmetrical diester of a 4-carbon atom dicarboxylic acid csterified with alkyl radicals selected from the group consisting of n-propyl and n-butyl and, as a synergist, a hetero-dicyclic compound selected from the group consisting of 3:4-methylene dioxy-6-propylbenzyl-n-butyl diethyleneglycol ether, n-octyl sulfoxide of isosafrole, and n-Z-ethyl hexyl imide of endomethylene tetrahydrophthalic acid.

14. A process for repelling flies from warm-blooded animals which comprises applying to said animals a symmetrical diester of a 4-carbon atom dicarboxylic acid esterified with alkyl radicals selected from the group consisting of n-propyl and n-butyl and, as a synergist 3:4- methylene dioxy-6-propylbenzyl-n-butyl diethyleneglycol ether.

13 References Cited in the file of this patent UNITED STATES PATENTS 1,727,305 Moore Sept. 3, 1929 2,274,267 Grawett Feb. 24, 1942 2,757,120 Leonard July 31, 1956 OTHER REFERENCES Eddy: Soap and Sanitary Chem, vol. 30, July 1954, p. 121.

Smith and Cole et al.: J. Econ. Entomol., vol. 47, February 1954, pp. 13-15 (p. 15 code'No. 671, 6052 relied on).

Smith and Burnett: J. Econ. EntomoL, vol. 42, June 1949, pp- 439-440.

Organic Chem, 0011. Outline series, Barnes and Noble, 1951, p. 73.

King: US. Dept. Agr. Handbook No. 69, May 1954, pp. 1-21, 176, 220, 316.

Soap and Sanitary Chem., March 1952, vol. 28, No. 3, pp. 136-137.

Drug and Cos. 1nd, January 1947, vol. 66, No. 1, pp. 44-47.

Frear: Chem. of Insecticide, Fungicides and Herbicides, D. Van Nostrand, 2nd ed., 1948, pp. 280-287.

Lindquist: J. Eco. Ent., vol. 37, No. 4, August 1944, pp. 485-486.

Linduska: I. Eco. Ent., vol. 39, No. 6, December 1946, pp. 767-769.

Pest Control Materials (1950), Frear and Hilborn, p. 22.

King: US. Dept. Agr. Handbook N 69, pp. 218, 219, 248. 

11. A COMPOSITION FOR REPELLING INSECTS COMPRISING, AS A REPELLENT, A SYMMETRICAL DIESTER OF A 4-CARBON ATOM DICARBOXYLIC ACID ESTERIFIED WITH ALKYL RADICALS SELECTED FROM THE GROUP CONSISTING OF N-PROPYL AND N-BUTYL AND, AS A SYNERGIST, A HETERO-DICYCLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF 3:4-METHYLENE DIOXY-6-PROPYLBENZYLN-BUTYL DIETHYLENEGLYCOL ETHER, N-OCTYL SULFOXIDE OF ISOSAFROLE, AND N-2-ETHYL HEXYL IMIDE OF ENDOMETHYLENE TETRAHYDROPHTHALIC ACID. 